[linux-dvb] [RFC]

Hari_Mohan wrote:
>> -----Original Message-----
> From: Manu Abraham [mailto:manu at kromtek.com]
> Sent: Wednesday, February 16, 2005 4:37 PM
> To: Hari_Mohan
> Cc: linux-dvb
> Subject: Re: [linux-dvb] [RFC]
>> Hari_Mohan wrote:
>>>-----Original Message-----
>>From: linux-dvb-bounces at linuxtv.org [mailto:linux-dvb-bounces at linuxtv.org]
>>On Behalf Of Manu Abraham
>>Sent: Wednesday, February 16, 2005 3:04 PM
>>To: Hari_Mohan
>>Cc: linux-dvb
>>Subject: Re: [linux-dvb] [RFC]
>>>>Hari_Mohan wrote:
>>>>>>>-----Original Message-----
>>>From: linux-dvb-bounces at linuxtv.org [mailto:linux-dvb-bounces at linuxtv.org]
>>>On Behalf Of Manu Abraham
>>>Sent: Wednesday, February 16, 2005 2:11 PM
>>>To: Hari_Mohan
>>>Cc: linux-dvb
>>>Subject: Re: [linux-dvb] [RFC]
>>>>>>Hari_Mohan wrote:
>>>>>>>>>>>>>I don't know much about this but I have seen this in a dvb demodulator
>>>>output and ASI convertors. These lines were termed DVALID and these used
>>>>>>to
>>>>>>>>>>>>>stay high whenever there is valid data in the transport stream
>>>>bus-8bit/serial. This line stays low when there are some special
>>>>>>characters
>>>>>>>>>>>>>coming in the bus. I think this flag is related to that. Even error line
>>>>also is similar - ie whenever there were some uncorrectable errors this
>> is
>>>>>supposed to stay low - depends on your configuration
>>>>>>>>>>What i was wondering was that, whether this information could help in
>>>the upper space DVB API/driver in any manner, in terms of error
>>>correction and or other aspects.
>>>------------------------
>>>According to my knowledge mpeg decoder chips will clock in the data based
>>>>on
>>>>>>>the state of these lines. I don't know whether any hardware mechanism is
>>>>>>So is this information more reliable than the 13818-1 Discontinuity flag..
>> ?
>>>such that this information can be used to identify cases where we have
>>problems in the TS.. ?
>>since under the Linux DVB API, we don't have an exact solution for
>>discontinuity, and TS errors to a 100% effectiveness, would these flags
>>be useful for solving that problem ?
>>>>For a particular DVB card, i can get these signals out from the frontend
>>to the card and the driver.. So, considering that aspect if i get these
>>flags out, i was wondering whether it would be possible to have a
>>solution for the latter errors..
>>>>That was the query that i had in my mind..
>>********************
>>>>The error bit which I am speaking about is the signal which is given by
>>demodulator or a receiver device once it finds that input ts packet is
>> Yes, that's the one what i was referring to..
>>>>errored. But the discontinuity indicator which you refered is inside the
>>transport stream - so these information which are inside stream are
>> inserted
>>>from the stream generator (encoder/mux) and I don't think that tuner will
>> be
>>>reading this data to give the error signal/flag.
>>> What i was thinking was that if the demodulator detects a broken stream
> and or inconsistencies, this would also result in broken TS's and CRC
> failures.
>>>>For discontinuity in transport stream you can tweak software or add some
>>patches but for errored input signal indication I don't think anything can
>>>> Some patches have already gone in regarding broken streams, but that
> still doesn't seem to solve all the issues.
> That only made me think in this aspect, as well as the availability of
> these flags. These cards do not feature a MPEG decoder.
>>> ~~~~~~~~~~~~~~~~~~~~~~~~~~
> I don't have much idea about v4l drivers but still if you can tell me the
> issues I can try some suggestions. If you are trying to record videos then
Broken TS's and CRC failures.. I see them once a while.. I still got to
find out where that happens though.
> you can avoid the bad vid pes packets. But if you are playing a video
> realtime you may face problems.
I am not trying to record a video here.. but rather playing it..
>> Hari
> ~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>>be done other than making satellite/cable reception proper.
>>> So do you mean to say that these falgs can be helpful only for MPEG
> decoders and so on ?
> When we are doing Software MPEG decoding, rather than Hardware doing it,
> would it be possible to make use of these flags ?
>>> @@@@@@@@@@@@@@@@@@@@@@
> Do you have APIs which give access to these flags. If you have it then the
> possibility can be explored. Which is the video codec s/w used in this?
It could be any codec.. Currently for the MPEG2 TS i am using mplayer.
>> Hari
> @@@@@@@@@@@@@@@@@@@@@@
>>>Hari
>>**************************
>>>>>>>there to store these values and use for upper layer applications. Because
>>>stv299 may have separate APIs to calculate BER and signal quality.
>>>>>>Hari
>>>---------------------------------
>>>>>>>>>>>>>>>>>>>>>>Hari
>>>>>>>>-----Original Message-----
>>>>From: linux-dvb-bounces at linuxtv.org>> [mailto:linux-dvb-bounces at linuxtv.org]
>>>>>On Behalf Of Manu Abraham
>>>>Sent: Wednesday, February 16, 2005 12:27 AM
>>>>To: linux-dvb
>>>>Subject: [linux-dvb] [RFC]
>>>>>>>>Hi,
>>>>>>>>Is there any advantage in getting the following flags out from the tuner
>>>>(STV0299 based).. such that it might be of some help.. ?
>>>>>>>>(1) data valid
>>>>(2) error
>>>>>>>>>>>>>>>
Manu